docs: def _build_params(self):
          """Have no idea why wrong params order can't get data.
          So, use `OrderedDict` here.
          """
          d = OrderedDict()
          d['purpose_codes'] = 'ADULT'
          d['queryDate'] = self._valid_date
          d['from_station'] = self._from_station_telecode
          d['to_station'] = self._to_station_telecode
          return d